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Tell us, Solly

Tim Radford

Solly Zuckerman: A Scientist out of the Ordinary by John Peyton
Murray, 252 pp, £22.50, May 2001, ISBN 0 7195 6283 X

Solly Zuckerman was one of a group of clear thinkers on both sides of the Atlantic who helped make science a normal part of government policy. He began at floor level in 1940, when the Royal Navy asked him to find out the force at which a leg would break. When a ship hit a mine and blew up, the vertical displacement of the deck was enough to snap the ankles of a seaman standing on it. When a torpedoed ship tilted and began to sink, and a seaman tried to slide down the exposed hull, his feet were likely to hit the bilge rail, with the same consequences. Would boots save them? Zuckerman and a colleague began dropping a corpse from gradually increasing heights through a kind of hangman’s trap and X-raying the legs each time until an ankle broke. Then they did the same thing with a second corpse, this time fitted with a heavy rubber-soled boot. ‘We found that boots did to some exent protect the ankle, but that the fracture that it might have suffered now occurred higher up the leg,’ he wrote in his first volume of autobiography, From Apes to Warlords (1978).

The Second World War was the first fullscale experiment in terror bombing and Zuckerman had already sorted out one mystery for the Medical Research Council and the National Physical Laboratory. Doctrine had it that the blast wave from a bomb would collapse or explode the lungs of anyone in its path. Zuckerman placed a series of rabbits in steel cages – with only their heads sticking out – at varying distances from an epicentre and then detonated his bomb. According to doctrine, the pressure should have blown the animals to pieces. In fact, they all survived. None lost consciousness and the only injuries were ruptured eardrums. He went on to establish that the pressure at which a blast would wound or kill increased with the body weight of the victim, and was roughly proportional to the surface area of the body. The pressure at which a man had a 50-50 chance of being killed turned out to be 500 lb per square inch, ten times higher than previously thought.

Zuckerman and his unit then began to look at injuries from high-velocity weapons and shrapnel fragments. These, too, presented puzzles. One man was in hospital after being hit in the kidney by something no bigger than a metal pinhead. A forearm had been shattered by a minute metal splinter. Zuckerman continued to use rabbits – served up for dinner afterwards – but the best results came from photographing a blob of gelatine as a bullet went through it. The stricken jelly expanded to four times its original volume as a cavity formed inside. Then it went through a series of pulses and collapsed to its original size. This kind of deformation, as energy was transferred from bullet to tissue, explained why small ordnance could do disproportionate damage at the highest velocities. A tiny metal sphere could shatter a rabbit’s thighbone even if it missed the actual bone by half an inch.

Such questions were not, after the fall of France and the beginning of the Blitz, in the least academic. Ninety per cent of the casing of a bomb turned into fragments weighing less than a 25th of an ounce. How helpful would body armour be against this shower of shards? The Zuckerman unit began firing standard steel balls into London telephone directories. According to the page at which a ball had stopped they could calculate how much energy it had lost when penetrating the target. They went from telephone books to human flesh, borrowing what Zuckerman called ‘anatomical material taken from, and returned to, a hospital post-mortem room’. The next trick was to work out wounding power according to the part of the body vulnerable to a blast. Volunteers were photographed nude, from the front, the back, sideways, kneeling and lying down. The idea was to work out how much flesh on average – the mean projection area – was at risk from a grenade or explosive. The answer was four square feet, of which 10 to 15 per cent covered vital organs. Wooden panels of this size, used by army operational research groups to measure wounding power, instantly became known as ‘zuckermen’.